Background

The ultimate goal for the HSM is providing quantitative methods to develop a safer,
more efficient roadway transportation system. The Manual achieves this goal by providing
information and tools in a useful format so practitioners, managers, and executives
can make the best decisions to reduce the number and severity of crashes on our
nation’s roadways. The HSM provides transportation professionals with knowledge,
techniques, and methodologies to quantify the safety-related effects of transportation
decisions. By using the HSM, practitioners can quantify crash frequency and severity
and integrate that information into roadway planning, design, operations, and maintenance
decisions.

The concept of developing a safety manual began at a conference session at the 1999
TRB Annual Meeting, it was determined there was an absence of and a need for a single
authoritative document to use for estimating safety impacts. Prior to this first
edition of the HSM, there were no widely accepted tools for engineers to use to
quantify the potential change in crash frequency and severity when making transportation
facility design and operations decisions. As a result, safety considerations often
carried little weight in the project development process, limiting the ability of
transportation professionals to discuss and act upon safety-related recommendations
during project development.

The formation of a joint TRB Task Force jump-started the development of the HSM
with support from the American Association of State Highway Transportation Officials
(AASHTO), Federal Highway Administration (FHWA), and Institute of Transportation
Engineers (ITE).

Today along with AASHTO, the Federal Highway Administration (FHWA) and the Transportation
Research Board (TRB), through the Highway Safety Performance Committee (ANB25),
coordinate implementation of the HSM and any additional research activities. The
Highway Safety Performance Committee fosters the development, validation, and increased
knowledge of science-based methods, procedures, and measures that will increase
the safety of the nation’s highways.

Target Audiences

The target audience for the HSM is primarily managers, executives, and practitioners
from five key groups:

Management – Professionals and managers from transportation
administration and other decision-makers;

The HSM, which does not require sophisticated data warehouses to make an impact,
is written for practitioners at the state, county, metropolitan planning organization
(MPO), or local level. The tools in the HSM are scalable so they can be implemented
by DOTs with robust data warehouses and processing capability or by local authorities
with little more than a laptop.

Benefits

The HSM is the key ingredient that will allow for quantitative safety performance
evaluation. This will:

Improve the decision-making process for applying safety treatments;

Demonstrate the impact on safety of various design alternatives;

Address specific needs;

Integrate safety elements in the most cost-effective manner;

Predict the change in crash frequency or severity associated with a particular improvement;
and

Allows agencies to do more with less by focusing resources on locations with the
highest potential for safety improvement.

By using the HSM, practitioners can:

Identify sites with potential for crash frequency or severity reduction;

Identify factors contributing to crashes and associated potential countermeasures
to address these issues;

Evaluate the change in crash frequency of implemented treatments;

Conduct economic appraisals of improvements to prioritize projects;

Calculate the effect of various design alternatives on crash frequency and severity;
and

Estimate potential crash frequency and severity on highway networks, and the potential
effects of transportation decisions on crashes.